The present invention relates to launch control of a vehicle having an automated manual transmission.
Clutches connected between the engine output and the transmission input are conventionally employed with vehicles having manual transmissions. The engagement of these clutches are controlled by a vehicle operator pressing on or releasing a clutch pedal. While these conventional manual transmissions have some drawbacks relative to conventional automatic transmissions—the need for the vehicle operator to actuate the clutch pedal and manually shift gears—they are still employed due to some inherent advantages. Namely, a conventional clutch and manual transmission is typically less expensive than a conventional automatic transmission and torque converter, and the conventional manual transmission arrangement does not have the energy losses associated with the torque converter.
Consequently, attempts have been made to develop a one or two clutch and manual type of transmission arrangement that will operate like an automatic transmission—an automated manual transmission or a powershift transmission. That is, employ a vehicle controlled clutch and gear shifting system, but without a torque converter or the more complex planetary gear sets and shift mechanisms of a conventional automatic transmission. One significant concern with these new systems, however, is the potential for heat build-up in the clutch during a vehicle launch (i.e., the transmission is in gear and the vehicle accelerates from a standstill). In order for a smooth launch of the vehicle from standing, there will initially be some slippage somewhere along the drive line. In the conventional automatic transmission arrangement, the torque converter allows for this slippage by shearing the fluid therein, with the torque converter readily having the thermal capacity to absorb and dissipate the excess heat generated. But for an automated type transmission with a clutch instead of a torque converter, the clutch will create the slippage, which creates heat build-up in the clutch. This heat build-up can occur relatively quickly, and can approach temperatures that may cause significantly increased wear and possibly damage the clutch.
Thus, it is desirable to have an automated manual transmission with a desirable launch function that prevents overheating of a clutch.